Interactive dental restorative network

ABSTRACT

An interactive dental restoration method and system for use between a dentist and a dental restoration laboratory. The method includes identifying a dental restoration need in a patient; designing a preliminary treatment plan that includes design criteria for preparation of a dental prosthesis to be placed in the patient to satisfy the dental restoration need; transmitting the preliminary treatment plan via a communications network to a dental restoration laboratory; and communicating a final treatment plan, including modifications to the preliminary treatment plan where necessary, to the dentist. The system includes a computer-based dental restoration system of a network server having a database storing information about materials, procedures and preparations concerning dental restoration prostheses; a communications network providing access to the network server; and one or more computers at a dental office accessing information stored at the database over the communications network and displaying the information in a humanly readable format. Preferably, the communications network is the Internet, and the information stored in the database comprises preparation diagrams, reduction dimensions, margin design and burs for specific dental restoration prostheses. Typically, the final treatment plan includes information about materials for preparing a dental prosthesis that satisfies the design criteria, and the dental prosthesis is then prepared for placement in the patient. This enables optimization of the dental restoration with significant savings in time and effort for the dentist, dental technician and the patient.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of application Ser. No. 09/443,368filed Nov. 19, 1999, which is a continuation of application Ser. No.09/411,920 filed Oct. 4, 1999, both now abandoned.

TECHNICAL FIELD

The invention is directed to methods, systems and devices for dentalrestoration wherein communication between the dentist and restorationlaboratory are held in real time to discuss, finalize and optimize atreatment plan for a patient. More specifically, the invention isdirected to an interactive computer-based system and method to enablethe dentist and restoration laboratory to analyze color images of one ormore teeth and teeth preparation so that a replacement tooth or crowncan be particularly designed to precisely match the tooth that is to bereplaced in certain clinical or cosmetic procedures.

BACKGROUND OF THE INVENTION

Restorative dentistry is the art and science of replacing or restoringlost tooth structure. The amount of tooth structure to be replaceddetermines what path the operator takes—whether the restoration will bea crown, bridge, inlay, onlay or direct restoration (i.e., a filling).The choice of that path in the past was more simple, due to the limitednumber of materials and techniques available. For example, U.S. Pat.Nos. 5,766,006 and 5,961,324 describe methods and systems fordetermining tooth color information based upon digital images providedby a camera and then matching the color of the restoration article(i.e., dental prosthesis) with the determined tooth color. In recentyears, however, with the advent of new materials and concepts, treatmentchoices have expanded in a phenomenal way. Dentists are now facing anoverload of information in trying to decide which materials andprocedures are the best suited for their particular cases. What thestate-of-the-art practitioner needs is a source to be able to go to, ata moment's notice, that will be able to aid him and his lab if necessaryin treatment planning and delivering the best restorative dentistrypossible, utilizing the most appropriate materials available today. Thepresent invention now satisfies this need.

SUMMARY OF THE INVENTION

The invention relates to an interactive dental restoration methodbetween a dentist and a dental restoration laboratory. The basic stepsof this method include identifying a dental restoration need in apatient; designing a preliminary treatment plan that includes designcriteria for preparation of a dental prosthesis to be placed in thepatient to satisfy the dental restoration need; transmitting thepreliminary treatment plan via a communications network to a dentalrestoration laboratory; and communicating a final treatment plan,including modifications to the preliminary treatment plan wherenecessary, to the dentist. Typically, the final treatment plan includesinformation about materials for preparing a dental prosthesis thatsatisfies the design criteria, and the dental prosthesis is thenprepared for placement in the patient. This method enables optimizationof the dental restoration with significant savings in time and effortfor the dentist, dental technician and the patient.

Generally, the dentist prepares the preliminary treatment plan and thedesign criteria include digital image representations of the dentalrestoration need. Thereafter, the preliminary treatment plan can beforwarded to and evaluated by the laboratory before a final treatmentplan is formulated and communicated to the dentist. The step oftransmitting and evaluating the plan are codirected over thecommunications network. Thus, the final treatment plan is notimplemented in the patient until after interim preparation informationis transmitted to the laboratory and confirmed, thus avoiding rework orrevision after the plan has been implemented.

Advantageously, the design criteria or the modifications thereto includeproposed decay excavation, tooth preparation, or dental prosthesiscolor. When a dental prosthesis such as a crown, bridge or replacementtooth is needed, the method includes verifying that the dentalprosthesis is prepared according to the final treatment plan prior toplacement of the dental prosthesis in the patient. In order to obtainthe best color match of the dental prosthesis with the patient's teeth,the digital image representations include REAL IMAGE and REFERENCEIMAGES and the modifications include correlation of a color selectionfor the dental prosthesis to match the REAL IMAGE. Furthermore, thedesign criteria can include tooth preparation and proposed decayexcavation, and the method further comprises a communication of aconfirmation or modification, from the laboratory, of the acceptabilityof one or more of the proposed design criteria.

The invention also relates to a computer-based dental restoration systemcomprising a network server having a database storing information aboutmaterials, procedures and preparations concerning dental restorationprosthesis; a communications network providing access to the networkserver; and one or more computers at a dental office accessinginformation stored at the database over the communications network anddisplaying the information in a humanly readable format. Preferably, thecommunications network is the Internet, and the information stored inthe database comprises preparation diagrams, reduction dimensions,margin design and burs for specific dental restoration prostheses.

Advantageously, the database further stores information concerning oneor more patients having dental restoration needs. Also, the networkserver further comprises application programs for enabling users toquery the database regarding specific materials or procedures concerningdental restoration prostheses for confirmation, verification,modification or evaluation of the same, with the one or more computersat the dental office receiving answers from the database to suchqueries. If desired, a printer located at the dental office can be usedto print these answers for use by the dentist in carrying out thetreatment plan.

The dental restoration laboratory also includes at least one computerthat has access to the network server and the computer(s) at the dentaloffice over the communications network. Preferably, the system includesa digital camera for taking digital images of the patient's teeth thatare in need of dental restoration and a communication link fortransmitting the digital images to the computer(s) at the dental office.Also, the computer(s) at the dental office store these digital imagesand the communications network forwards the digital images to thedatabase for storage therein.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other aspects of the invention should be more apparent fromthe following detailed description and drawings in which:

FIG. 1 illustrates a shade analyzer system for capturing images inaccord with a specific embodiment of this invention;

FIG. 2 shows a representative image captured by the system of FIG. 1;

FIG. 3 shows a representative image made up of pixels as captured bydetector elements of the system in accord with the invention;

FIG. 4 illustrates processing of the image of FIG. 3 usingpseudo-pixels, in accord with one preferred embodiment of the invention;

FIG. 5 shows an end piece constructed for use with the system in FIG. 1,for simultaneous processing of an actual tooth image and variousreference tooth shades;

FIG. 6 illustrates a compression sleeve constructed according with aspecific embodiment of the invention for capturing high-quality toothimages;

FIG. 7 illustrates a source-to-tooth illumination, for improved imagecapturing in accord with one embodiment of the invention;

FIG. 8 illustrates baffling and stray-light rejection within a sleeve ina specific embodiment of the invention;

FIG. 9 illustrates different pseudo-pixel imaging mechanisms, optionallydependent upon tooth shape characteristics, used in accord with theinvention;

FIG. 10 illustrates a non-contact tooth imaging system, with stray lightrejection, constructed according to a specific embodiment the invention;

FIG. 11 illustrates another embodiment of a non-contact tooth imagingsystem in accordance with the present invention;

FIG. 12 illustrates a digital image of a tooth;

FIG. 13 illustrates a system for reimaging a tooth;

FIG. 14 illustrates various tooth decay patterns and restorations thatcan be addressed in accordance with the present invention;

FIG. 15 is a schematic representation of the interactive network systemof the invention.

FIG. 16 is a block-diagram of the configuration of the interactivenetwork system of the invention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention now provides an enhanced dental restorationnetwork as a service for dentists. This network would be established viaa computerized link between the dentist, the lab, and, optionally, thelab's databank of the most current information regarding materials,procedures, and other services such as preparation design and surveyingfor dental restoration prostheses such as caps, crowns, bridges,fillings and the like.

In a typical case, initial steps of complete examination and diagnosisof the patient's dental condition is by the dentist. This generallyincludes a basic periodontal examination, clinical exam, radiographs,screening for TMD, etc. The dentist also creates a preliminary treatmentplan for addressing the dental needs of the patient. When tooth cappingor replacement is required, clinical pictures which can are taken andcaptured on a program and are forwarded to the lab. Theses pictures canbe of the color of the patient's teeth, the preparation of a tooth forfurther treatment, or even of a temporary treatment which can bemodified or enhanced before being finalized. The pictures can be takenin any one of a number of ways, as described in more detail below.

In this invention, an on-site advanced restorative system is providedwhere the dentist takes one or more digital images of the tooth prior torestoration, eliminates areas of decay in the image, and matches theshade of material to be used to restore the tooth based upon the digitalimages of the tooth prior to removal. In another aspect, the dentisttakes digital images of the tooth after preparation and matches theshade of the material to be used in restoration based upon the remainingparts of tooth. These pictures can be forwarded by facsimile, directcomputer link, or by e-mail to the lab for evaluation, along with thedentist's preliminary treatment plan.

After preliminary treatment plans are designed, and areas such asperiodontal needs, decay excavation, endodontic concerns are addressed,the restorative needs are considered. If the treatment plan may includefixed prosthodontics (crowns and bridges), the clinical pictures arethen forwarded to the lab. The doctor and technician assess the casetogether prior to accessing the interactive dental restorative network(“the site”). An illustration of such a network is shown in FIG. 16 anddescribed in more detail below. If the case involves only directrestorations, the dentist can go directly to the site.

If the dentist does not have access to the site but his lab does, thedoctor could send pictures to the lab, the technician in turn couldaccess the site, and consult back to the doctor giving restorativeoptions as given by the site. This service would be rendered by the labsfor dentists that are not comfortable or familiar enough with computersto do their own electronic processing and communication with the site.

The site would provide access for users to information on materials,procedures involved in using such materials such as preparation design,recommended burs to achieve such a preparation, recommendedtemporization materials, cements that should be used with that givenmaterial, instructions on how to use such a cement (i.e., conditionssuch as whether one should etch or prime, for how long, whether to dryit or not, to pre-cure it or not, etc.), and where to buy suchmaterials. Alternatively, the lab could explain how it would providesuch a service or who the dentist could contact to obtain such service.Beyond this, once the treatment is underway, the dentist could verifyhis preparation with the technician, if necessary, by sending digitalimages electronically for review prior to final impressions. For a moreprecise evaluation of the case in treatment, the dentist would scan hispreparations and go to part of the site that would survey the teeth andassess reduction amount. This would typically be used in larger and morecomplex cases.

The site would offer a number of features for communicating dentalrestoration data to the dentist and technician. One of the most uniquefeatures of the site is that it is interactive. Rather than just being adatabank of information for the dentist to review, the dentist would beled through a step by step procedure to determine the most appropriaterestorative path to take. The site could be visited periodically toconsider alternative procedures, different options or to just confirmthat the previous recommendations are clear and are being followed.Although many dentists read articles and reports, and attend seminars toobtain the latest information, until there is a case in hand, a lot ofthat information is not applicable. By the time a given case correspondsto a case presented at a previous seminar, the dentist may have alreadyforgotten the information. The present method and system providesimmediate feedback of the most up-to-date information in real time forthe specific need of the current patient.

As the dentist accesses the site, he can immediately be asked certainquestions regarding the patient's history. Typical questions underconsideration for dental restoration procedures include: Are esthetics amain concern? Is the patient a bruxer (i.e., heavy grinder)? What is theextension of the patient's smile—give the teeth numbers of the limits ofwhat is visible on their widest smile? Does the patient have a high lipline, i.e., does their lip lie below the incisal edge, midtooth, at thecervical margin, above the cervical margin? Do they show mandibular(lower) teeth when they smile? Is the opposing occlusion natural? Ifnot, is it metal, porcelain, amalgam, composite or denture teeth? Byproviding the restoration lab with this additional information, allfactors can be considered so that a sound, tailored treatment plan canbe confirmed or recommended.

The laboratory then would consider the teeth in question: Are theyanterior or posterior? Endodontically treated or vital? What shade arethey initially? What is the desired shade? What is the prepared toothshade? (Information on how to obtain the color of the teeth is disclosedin the other application—please insert here) What are the dimensions ofthe tooth—is it a short clinical crown, or average to larger thanaverage in size? Are there any implants involved? The process wouldoperate like an “elimination tree”—if the first question of estheticconcern was a “no”, the site would not go on to ask smile dimensions andsuch. All questions would be answered to a point to compile a profile,and any given patient may require their case to be divided into morethan one profile depending on the scope of their needs, saycorresponding to sections of their mouth in quadrants.

Another issue to be addressed is that of materials. This would give thematerial name, its characteristics and properties, and why it wassuggested. Suggested is the operative word here because it should beunderstood that ultimately it is the dentist's choice of treatmentmodality that is used and not that of the technician or the site. Afterthe dentist chooses the material, he would need to know where to obtainit, if he didn't already have access to it. This would entail thedentist purchasing a direct material, either through the site to anordering area, or being referred to a lab in his area that uses such asystem.

The issue of preparation design when planning to use that given materialis also addressed by the site. Different materials demand differentsubstructures and margins. There are not a tremendous number ofdifferent designs needed. Within the site, there is a file ofpreparation diagrams, which could be printed out by the dentist, ifnecessary, to provide reduction dimensions, margin design and the bursneeded to do this. This would include bur name and number, type andwhere to obtain them. Once again, the dentist may order this through thesite or obtain information or where it could be purchased in his area.The dentist could simply obtain all materials from the site compile ashopping list for this particular procedure and go out and obtain thematerials on his own.

Once the case is underway, and the initial preparations are completed,the dentist could go back to the site and scan the preparations toassure compliance. Alternatively, digital representations of thepreparations could be sent back to the site or lab for their furtherreview. A of the preparations can also be made by accessing a surveyarea of the site. This would evaluate the preparation for undercuts,under-reduction, margin extension, and highlight areas that needed to bemodified for optimum results.

Communication with the site in real time would save a great amount oftime and effort. By first confirming that the preparations andrecommended dental restoration procedures are correct, the lab would nothave to be pouring and working on models of a case that were not useablebecause the preparations required changing. Also saved would be the timeof having the patient return to the office on multiple occasions forrefining preparations. This is a significant benefit for both dentist,patient and laboratory. By providing the laboratory operator with suchinformation without taking an impression, pouring up models andsurveying them with a traditional surveyor, both time, materials andexpenses due to re-work are saved.

Another advantage of real time evaluation is reduction. One of the mostcommon errors in preparation is under-reduction (i.e., not removingenough tooth structure to allow room for the materials that will make upthe crown or restoration), which causes either too thin of restorationin that area which can lead to future failure, or repreparation (i.e.,more wasted chair time) and new impressions or reduction copings. Withinthe survey site, the dentist would be able to more accurately scan thepreparation with the teeth in occlusion so as to measure the amount ofreduction to the tenth of a millimeter. Then, the dentist would comparethis measurement to the given specifications of the preparation he hadretrieved earlier from the preparation design area of the site toconfirm compliance.

Another use of the present interactive dental restoration network is theverification of the final dental prosthesis before it is permanentlyplaced in the patient's mouth. For example, when a crown is finallyprepared, digital images can be taken and compared to the digital imagesof the patient's teeth that were previously obtained to assure that theclosest color match has been achieved. Any necessary color correctionscan be made by the laboratory or the technician before permanentplacement of the crown. This again saves time by avoiding rework whenthe patient returns to the dentist's office for the installation of thecrown.

A number of different aspects of determining tooth shade color aredisclosed. For clarity of presentation, these aspects are organized anddescribed below in sections which are not intended to be limiting in anyway.

The Color Determination Method

With reference to FIG. 1, a solid state camera 12 (e.g., a CCD cameracoupled to a PC board, or an intra-oral camera) is utilized to captureone or more images of each known conventional tooth shade. Tooth shadesused to this end may correspond, for example, to the VITA™ Shade guide,or a shade guide corresponding to a porcelain by another dental productsmanufacturer. By way of example, a first series of images taken inaccordance with the invention corresponds to sequential images of the Alshade by Vita, a second series of images corresponds to sequentialimages of the A2 shade by Vita, and so on. In accordance with theinvention, captured image series of the known tooth shade guides areproperly labeled and then stored onto the hard disk of the computer, orother suitable storage device for further analysis. FIG. 2 illustrates arepresentative digital image 30 captured by the camera 12.

As known in the art, each digital image has a plurality of pictureelements, i.e., “pixels”, corresponding to the elements of the solidstate camera and representing the light intensity and color propertiesof a given spatial location on the tooth. The distance between adjacentpixels in the image is determined by the spatial resolution of thecamera. For example, an image of a tooth shade (or a human tooth) can bemade up of 300 pixels in width across the tooth and 350 pixels inheight. In human teeth, any given tooth is approximately the same size,give or take a couple of millimeters, for all people. For example, mostcentral incisors usually measure between 9-11 mm in width, and somewhatgreater in length It is clear therefore that for a given spatialresolution of the camera, in accordance with this invention an image ofa tooth can be taken knowing the approximate number of pixelscorresponding to the tooth in the image. Thus, in the example above, 1mm of the tooth width may be represented by 30 pixels. It will naturallybe appreciated that the tooth image is typically not rectangular, andthat pixels at the corners 41 of an image may correspond to thebackground (i.e., the region outside of the tooth) and not of the toothor tooth shade. See FIG. 2 for further illustration.

As indicated above, a single digital image can be captured for eachtooth shade or actual tooth. Those skilled in the art will appreciate,however, that taking a series of images per shade is preferable, sinceit reduces the risk of image anomalies, as explained in further detailbelow.

Next, each image or each image in a series is processed into a “pseudo”reference image (hereinafter PSEUDO IMAGE) made up of pseudo-pixels. Asused in this disclosure, pseudo-pixels correspond to groups of pixelscovering specific areas (e.g., rectangular or square) of the imageplane. FIG. 3 shows a blow up image of the pixels 42 (onlyrepresentative pixels 42 are shown) which make up the tooth image 40 ofFIG. 2. In accord with the invention, these pixels are transformed intopseudo-pixels 44, as shown in FIG. 4. In the embodiment illustrated inFIG. 4 each pseudo-pixel 44 is made up of all or some of thereal pixelswithin the area of the associated pseudo-pixel. Pseudo-pixels 44 b shownin the figure illustrate, for example, how a pseudo-pixel can begenerated from nine real pixels 42. FIG. 4 also illustrates that animage can be made from either a real tooth 40 (resulting in a REALIMAGE) or a reference shade 40 (resulting in a REFERENCE IMAGE).

FIG. 9 shows how pseudo-pixels can be arranged in a preferred embodimentin different patterns, automatically, depending upon which tooth isimaged. For example, an incisor 200 can have an arrangement ofpseudo-pixels 202, as shown in the left-hand example, while a molar 204can have an arrangement of pseudo-pixels 206, as shown in the right-handexample. With further reference to FIG. 1, such arrangements can be madeautomatically in the system of this invention by informing the computer14, and hence the software 50, to apply pseudo-pixels in the appropriatepattern. Such arrangements assist in overall processing by ensuringappropriate pseudo-pixel placement. As illustrated in FIG. 9,pseudo-pixels need not be contiguous, or aligned, such as shown by thearrangement of pseudo-pixels 206.

In a preferred embodiment, the intensity and color associated with apseudo-pixel are computed or otherwise formed as an average (or otherstatistical measure) of the actual pixels forming the pseudo-pixel. Byway of example, if an actual image taken in the first step of the methodcorresponds to a rectangular tooth that is digitized at 300W by 350Hresolution, i.e., having a total of 300×350 elements, in accordance withthis embodiment one can create pseudo-pixels such as 6W by 7H, with eachpseudo-pixel being formed as a statistical measure of the 50×50 pixelswithin the pseudo-pixel (resulting in 42 pseudo-pixels representing theentire tooth).

As noted above, in accordance with a preferred embodiment, pseudo-pixelsare generated by data derived from all or some of the actual pixelslocated within the pseudo-pixel. For example, in a specific embodimentone can average the red, green and blue (RGB) components for each of the2500 pixels within each pseudo-pixel to determine a reference RGB forthat pseudo-pixel. Those skilled in the art will appreciate that otherstatistical measures or characteristics can be used, such as the mean“hue” measure of the pixels within a pseudo-pixel, or others. Forexample, the RGB pixel values may be converted into the Hue, Saturationand Intensity (“HSI”) color space by using known algorithms, such as theGonzalez and Woods method, as follows:

R=Red value for pixel

G=Green value for pixel

B=Blue value for pixel

Intensity=⅓ (R+G+B)

 Saturation=1−(3/R+G+B))*Min(R, G, B)

Hue=Cos⁻¹((0.5*((R−G)+(R−B)))/((R−B)*(G−B))^(0.5))

If S=0, Hue is meaningless

If (B/Intensity)>(G/Intensity) then Hue=360−Hue

RGB corresponds generally to three different pixels

Since Hue is an angle in degrees values were normalized to 0.1 withHue=Hue/360

As known in the art, the RGB color space can be represented as a simplecube, with R, G and B emanating from one corner along threeperpendicular edges. The origin corner (0,0,0) is black, and theopposite corner (1,1,1) is white. All points along this line from cornerto corner are shades of grey. The HSI color space is this same cubestood on the origin corner, with the Black White line being vertical.The black—white line is the intensity axis, the hue is given by an anglefrom the intensity axis and the saturation is the distance from theintensity axis to the color point (i.e., the radius). The new VITAPAN3D-Master Shade system uses an L*a*b* Color Sphere to determine toothshades based on Value, Chroma and Hue. It is possible to convert the RGBvalues to this color system, if necessary or desired.

In accordance with a preferred embodiment, PSEUDO IMAGES are processedthen into a “REFERENCE IMAGE”. By way of example, the REFERENCE IMAGE isgenerated as an average (or other statistical measure) of the PSEUDOIMAGE series of images of the VITA™ A2 shade guide. The measure in thisexample is obtained by averaging the R, G, B components for eachpseudo-pixel of the A2 PSEUDO IMAGE series to determine an average RGBvalue for a pseudo-pixel of the REFERENCE IMAGE. In alternativeembodiments operating in the HSI color space, the corresponding averagevalues can also be determined for each pseudo-pixel of the PSEUDO IMAGEseries; and, for example, an average hue (or other statistical measureof hue) can also be associated with each pseudo-pixel in the REFERENCEIMAGE. Those skilled in the art will appreciate that other colorcharacteristics can be used alternatively or in conjunction with themeasure of RGB and/or hue. It will be appreciated that if only onePSEUDO IMAGE is made per shade, than that PSEUDO IMAGE defaults as theREFERENCE IMAGE since no other statistical combination is available.

It should be noted that forming of pseudo-pixels is not a requirementfor practicing this invention. However, pseudo-pixels are used in apreferred embodiment because they may reduce the processing load of thesystem, minimize storage requirements and also because they can simplifythe task of aligning corresponding pixels from different images. Properpixel alignment is important in order to ensure the integrity andaccuracy of the statistical averages used in the formation of REFERENCEIMAGES. In this regard it will be appreciated that it is generallydifficult to precisely align all pixels in several images taken from theshades of the same shade guide, unless there is extremely good controlutilized in the image capture sequence. Using pseudo-pixels inaccordance with the preferred embodiment reduces the total number ofpixels per image and thus simplifies the task of aligning differentimages accurately.

Pseudo-pixels are even more important in later steps of the processingmethod of this invention. That is, although one has complete freedom toset up the optics and the camera, which together determine themagnification of a captured tooth shade (or tooth) image, when trying to“match” a REFERENCE IMAGE to an actual digital image of a patient'stooth, the actual image (hereinafter referred to as a SNAPSHOT) may bequite different in shape and size (either real size or apparent size dueto magnification differences in the optics or camera CCD element size).As such, a “one-to-one” comparison between the SNAPSHOT and theREFERENCE IMAGE is difficult. Pseudo-pixels help in this respect becausethe SNAPSHOT can be scaled to approximate the REFERENCE IMAGE size, orvice versa; and the SNAPSHOT can also be processed into pseudo-pixels.The scaled and pseudo-pixel version of the SNAPSHOT image is denoted asthe “REAL IMAGE” hereinafter. Pseudo-pixels used in a preferredembodiment thus permit a convenient mechanism for comparing a REFERENCEIMAGE to a REAL IMAGE.

In accordance with a preferred embodiment, the generation of eachREFERENCE IMAGE preferably includes a “bad pixel” routine where eachpseudo-pixel in the PSEUDO IMAGE series is analyzed for bad pixels. A“bad pixel” means any real pixel corresponding to a defective CCDelement or corresponding to an area with an unwanted artifact, e.g.,reflection, in the digital image, or an area that contains “background”imagery (e.g., any pixel image not corresponding to the tooth or toothshade). Any pseudo-pixel in the PSEUDO IMAGE which contains a bad pixelis preferably not utilized in the generation of the REFERENCE IMAGE.That is, if for example a REFERENCE IMAGE is made up as an average ofthree PSEUDO IMAGES, and yet one pseudo-pixel in one of the PSEUDOIMAGES contains a bad pixel, then in a specific embodiment the resultingpseudo-pixel of the REFERENCE IMAGE is either discarded, or computedonly as an average of the other two associated pseudo-pixels of thePSEUDO IMAGES.

Note that the bad pixel routines are particularly important at the edgesof the image of the tooth or tooth shade. Consider, for example, theshape of the tooth 40 in FIG. 3 or the irregular shapes illustrated inFIG. 14. Clearly, such shapes are not rectangular, and thus creatingpseudo-pixels in accordance with the preferred embodiment will result incertain pseudo-pixels having bad pixels at the image edge. FIG. 4illustrates bad pseudo-pixels 44 a that contain pixels 42 a, which arenot part of the tooth image 40. Bad pixel routines used in accordancewith a preferred embodiment to detect such pixels and disqualify themfrom further processing. For example, if 5% or more of the pixels withina pseudo-pixel are “bad” (e.g., containing reflections or other unwanteddata), then such pseudo-pixels are disqualified. Though not shown, otherpseudo-pixels might be disqualified if for example reflections from thelight ports cause unwanted reflections in the other pseudo-pixels image40. In a preferred embodiment, such pseudo-pixels are deleted frominclusion in the REFERENCE IMAGE.

In a specific embodiment, the bad pixel routine need only be implementedwhen capturing and generating REAL IMAGES. In that process, conditionssuch as lighting and other variables can create unwanted artifacts thatshould be eliminated from processing. In addition, when cameras are usedin the field, one pixel might become defective over time; and REALIMAGES later generated from the defective camera should be adjusted sothat the pseudo-pixel which contains the bad pixel is not counted orutilized.

In another aspect, areas of the tooth for which the color is to beevaluated are predefined, allowing the analyzer program operating inaccordance with this invention to batch-process the images. For example,a sample image can be loaded into an Area Selection Editor programmodule, where adjustments can be made to user-selected (or predefined)areas of the tooth image. These defined areas are then applied to eachimage in turn, and the pixel colors within each area are analyzed. Inoperation, following the image capture in one embodiment the method ofthis invention proceeds to automatically select the area(s) of thesample for analysis, for example, by applying a general rule to locatethe edges of the tooth in the image, and applying a predefinedsegmentation of the remaining area for analysis. Preferably, the user isallowed to manually select an area of interest in the image, forexample, using a computer mouse, as known in the art.

In accordance with one embodiment, following the detection of thecorrect areas for analysis (i.e., excluding edges, light reflections andother unwanted artifacts), the selected area is divided by using, forexample, a grid overlay, as shown in FIG. 9. As known, each shade has avarying color content from top to bottom. Therefore, in accordance withthis embodiment a more accurate analysis of the entire surface ofinterest can be made if color determination and matching is applied tothe individual cells of the grid, as compared with corresponding areacells of the stored color reference model for each shade guide.

Following this stage, in a preferred embodiment before analyzing thearea, various filtering operations can be applied to the image, as knownin the art. For example, filtering is applied to eliminate abnormalitiessuch as lamp reflections or dark spots. In addition, maximum, minimumand average values for the R, G and B components can be determined overthe area of interest and used to, for example, limit the variation fromthe average value to half way to the maximum and minimum values. Thissimple filtering operation has shown satisfactory results in actualtesting, although alternative or additional filtering operations can beapplied, as known in the art in order to obtain a standard image.

In the next step of the method, a SNAPSHOT of a patient's tooth is takenby the camera. Next, the digital image of the SNAPSHOT is scaled, ifnecessary, to approximate the size of the corresponding REFERENCE IMAGE.In the preferred embodiment SNAPSHOT pixels are next processed intopseudo-pixels resulting in a REAL IMAGE containing pseudo-pixels, whichsubstantially correspond to REFERENCE IMAGE pseudo-pixels. A bad pixelroutine preferably processes the REAL IMAGE to delete REAL IMAGEpseudo-pixels containing a bad pixel. As above, the bad pixel routine isparticularly important at the edges of the tooth image within theSNAPSHOT, where some pixels will certainly contain background (unlessthe camera and optics are arranged to capture only the tooth; howeverthis is not efficient since effective matching between the REAL IMAGEand the REFERENCE IMAGE occurs when a larger area of the tooth is usedin the comparison algorithms, which are defined in further detailbelow).

In a subsequent step, the REAL IMAGE is compared (i.e., correlated) toeach REFERENCE IMAGE in the database (e.g., there could be sixteenREFERENCE IMAGES corresponding to the A1-A4, B1-B4, C1-C4 and D2-D4 VitaShades) via the correlation algorithm (hereinafter “CorrelationAlgorithm”) described below. In this step, each pseudo-pixel of the REALIMAGE is compared to each pseudo-pixel of the REFERENCE IMAGE; and acomposite match number (“CMN”) is created indicating how well the REALIMAGE matches to that REFERENCE IMAGE. The composite match numbers arecompared to one another and one of the REFERENCE IMAGES is selected asthe “best fit” match to the REAL IMAGE.

There is potentially a problem associated with the bad pixel routine andsubsequent correlation between REAL IMAGES and the series of REFERENCEIMAGES. As described above, in a specific embodiment, when there is abad pixel in any pseudo-pixel, all other pseudo-pixels of the samespatial location are discarded. This can become a problem in a case whenevery (or even most) pseudo-pixel is disqualified, resulting in asituation where no meaningful comparison can be made. Accordingly, in apreferred embodiment, images are correlated on the basis of mathematicalmeasure, i.e., an average, that is functionally dependent upon how manypseudo-pixels remain in an image (REAL or REFERENCE). That is, for anygiven correlation between a REAL IMAGE and a REFERENCE IMAGE, the numberof pseudo-pixels for that comparison are used as a ratio for comparisonto other correlation. This aspect of the invention is described in moredetail below.

In an alternative embodiment, the averaging technique discussed above isused only when, for example, more than 20-25% of the pseudo-pixels aredisqualified for all comparisons. Accordingly, so long as there is asufficient number of remaining pseudo-pixels for comparison, a directcomparison of these pixels can be made without resorting to averages. Ina specific embodiment, a sufficient number is deemed to be about 75-80%of the total number of pseudo-pixels available for comparison. Otherratios can be used in alternate embodiments.

Bad pixel routines are generally known in the art and thus need not bedescribed in much detail. It is sufficient to note that in accordancewith this invention a pixel is determined to be “bad” if its lightintensity or color values deviate by more than a certain predefinedpercentage from adjacent pixels known to be “good”. For example, if apixel deviates by more than 30% from the light intensity of theneighboring 8 pixels, there is a good likelihood that this deviation isanomalous, i.e., due to a bad camera element or corresponding to animage border, and has to be discarded.

In a preferred embodiment, a pseudo-pixel is validated only when itcontains less than a certain percentage, i.e., about 5%, bad pixels ofthe total pixels making up the pseudo-pixel. Preferably, bad pixels arealso not used in the statistical characterization (e.g., RGB) of thepseudo-pixel. Accordingly, in this embodiment if more than about 5% badpixels exist for a pseudo-pixel, the pseudo-pixel is not used in furtherprocessing.

Correlation Algorithms

In a preferred embodiment, the Correlation Algorithm of the presentinvention operates as follows. Each REFERENCE IMAGE is actually a matrixof vectors, each vector corresponding to a pseudo-pixel. By way ofexample, the REFERENCE IMAGE corresponding to the Al Vita Shade can beassigned as vector Z_(A1). For the sixteen Vita Shade guide, theremaining fifteen shades for example each have a REFERENCE IMAGE too,e.g., Z_(A2), Z_(A3), etc.

Each REFERENCE IMAGE vector “Z”—corresponding to shade guide orporcelain “X”—thus has data similar to the following matrix:$Z_{X} = {{\begin{matrix}{PP}_{x,1} \\{PP}_{x,2} \\{PP}_{x,3} \\\cdots \\{PP}_{x,n}\end{matrix}} = {\quad \begin{matrix}R_{x,1} & G_{x,1} & B_{x,1} \\R_{x,2} & G_{x,2} & B_{x,2} \\R_{x,3} & G_{x,3} & B_{x,3} \\\cdots & \cdots & \cdots \\R_{x,n} & G_{x,n} & B_{x,n}\end{matrix}\quad }}$

where each of the pseudo-pixels “PP” has three values for each of R, Gand B values of the pseudo-pixel (actually, the RGB values are thestatistically computed (e.g., averaged) composition of the images in theseries for that REFERENCE IMAGE, if available). The subscript “x” refersto the appropriate shade, e.g., “A1”. Subscripts 1−n define separatepseudo-pixels in the REFERENCE IMAGE. Those skilled in the art willappreciate that additional, other or different data can make up eachvector, including hue data for each pseudo-pixel. Additionally, othervectors can be considered and processed in the correlation, such as hueand RGB values.

In a typical example, each REFERENCE IMAGE might have 20×20pseudo-pixels which define the REFERENCE IMAGE. Therefore, “n” in theabove matrix is 400.

When a REAL IMAGE “I” is generated, in accordance with this invention ittoo is arranged as a matrix of similar form, with each pseudo-pixel “PI”of the REAL IMAGE being a vector of RGB form (or, like above, containingother or additional factors such as hue): $I = {{\begin{matrix}{PI}_{x,1} \\{PI}_{x,2} \\{PI}_{x,3} \\\cdots \\{PI}_{x,n}\end{matrix}} = {\quad \begin{matrix}R_{i,1} & G_{i,1} & B_{i,1} \\R_{i,2} & G_{i,2} & B_{i,2} \\R_{i,3} & G_{i,3} & B_{i,3} \\\cdots & \cdots & \cdots \\R_{i,n} & G_{i,n} & B_{i,n}\end{matrix}\quad }}$

In a specific embodiment, the Correlation Algorithm used in accordancewith the present invention computes a measure of closeness, i.e., acomposite match number (“CMN”) through the following relationship:${CMN}_{x} = {{\sum\limits_{q = 1}^{n}\quad \sqrt{\left( {Z_{x,q} - I} \right)^{2}}} = {\sum\limits_{q = 1}^{n}\quad {\sqrt{\left( {{PP}_{x,q} - {PI}_{q}} \right)^{2}}\quad \text{or}}}}$${CMN}_{x} = {\sum\limits_{q = 1}^{n}\sqrt{\left( {R_{x,q} - R_{i,q}} \right)^{2} + \left( {G_{x,q} - G_{i,q}} \right)^{2} + \left( {B_{x,q} - B_{i,q}} \right)^{2}}}$

Once the CMN number is computed for each tooth shade, as shown in theexample above, a search is then conducted for the lowest CMN_(x) to findthe best fit REFERENCE IMAGE for the REAL IMAGE. That is, the toothshade or porcelain “X” is identified for the lowest associated value ofCMN. As noted above, if there is more than a certain percentage of badpixels in any pseudo-pixel q for either the REFERENCE IMAGE or the REALIMAGE, in a preferred embodiment that pseudo-pixel is not used in thevaluation of CMN. For example, in accordance with the present inventionit is acceptable to determine CMN without the q-th pseudo-pixel;however, every other concurrent q-th pseudo-pixel valuation of CMN_(x)in identifying the composite match number is also discarded, so thatCMNs for all tooth shades can be compared correctly.

As noted, the Correlation Algorithm of the embodiment illustrated abovepreferably uses a bad pixel routine to disqualify bad pseudo-pixels. Itwas noted already that this can create problems in certain situations.Accordingly, in a preferred embodiment, the following alternativealgorithm can instead be used:${CMN}_{x} = {\sum\limits_{q = 1}^{n}\sqrt{\left( \frac{R_{x,q} - R_{i,q}}{{Pcount}_{x}} \right)^{2} + \left( \frac{G_{x,q} - G_{i,q}}{{Pcount}_{x}} \right)^{2} + \left( \frac{B_{x,q} - B_{i,q}}{{Pcount}_{x}} \right)^{2}}}$

In this embodiment for the computation of CMN Pcount_(x) corresponds tothe number of common pseudo-pixels found between the REAL IMAGE and thevector Z_(x). Note that Pcount_(x) can be different for each CMNcorrelation. For example, if the REAL IMAGE has 400 pseudo-pixels, allgood, and REFERENCE IMAGE for A1 has 399 pseudo-pixels (e.g., one badpseudo-pixel identified in the bad pixel routine), then Pcount_(A1) is399. If however the REFERENCE IMAGE for B4 has 256 pseudo-pixels, thenPcount_(B4) is 256. If in the same example the REAL IMAGE has 256 validpseudo-pixels—and in the unlikely event that the disqualified REAL IMAGEpseudo-pixels overlap with the coordinates of disqualified pseudo-pixelsin the REFERENCE IMAGE—then Pcount_(B4) is still 256; howeverPcount_(A1) is also 256 (assuming that the one bad pixel of REFERENCEIMAGE A1 corresponds to one of the disqualified pseudo-pixels in theREAL IMAGE). If the one bad pseudo-pixel in REFERENCE IMAGE Al does notcorrespond to coordinates of one of the disqualified pseudo-pixels ofthe REAL IMAGE, a more likely event, then Pcount_(A1) is also 255.

Those skilled in the art will appreciate that isolating the measure ofcloseness CMN in one of the above equations can also be determinedwithout the square root operation—as a minimum composite match numberwill still be identified for the same functional conditions and/or data.

In accordance with the specific embodiment described above, the processof determining Pcount_(x) can be made at any point. In a preferredembodiment, this process is initiated only after a certain percentage ofpseudo-pixels are disqualified. For example, if after the completion ofthe bad pixel routine there remain 300 pseudo-pixels for comparison (inthe example that 400 pseudo-pixels exist in each of the REFERENCE andREAL IMAGES), then a straight comparison can be made without the use ofthe Pcount_(x) adjustment, because a significant percentage of theimages can be compared (defining 75% as “significant”; other percentagescan be used). Note that it is likely that many of the bad pixel areas inimages will overlap, such as at the edge of the image, where tooth shapevariations occur often, and at locations such as reflection areas (e.g.,areas which specularly reflect light energy to the camera), which arelikely to be similar given that the illumination source is generallyfixed for each image acquisition.

Those skilled in the art will appreciate that variations to theabove-described methodology may occur without departing from the scopeof the invention. For example, other color detection techniques can beused to characterize tooth color within a pseudo-pixel. In one example,colorimetric “laser-diode” measurements can be used to generate areflection trace for each pseudo-pixel. In such measurements, a laserdiode is “scanned” in wavelength so that a laser beam, scanned through arange of wavelengths, reflects off of each pseudo-pixel. Thisspectrophotometric-like trace information (for example containingreflectance per wavelength) can be collated with other such traces forother pseudo-pixels to generate a vector of such information. As above,correlation between real and reference vectors is used to determine abest-fit color match.

In accordance with another embodiment of the present invention, thecamera used for capturing images has a focal plane array with fewerdetector elements as compared to typical high resolution arrays (forexample those arrays with 640×480 elements, or megapixel digitalcameras). For example, in one embodiment of the invention an array has arelatively small number of detectors, i.e., 20×20, 60×40 or others. Sucha camera can alleviate the need for pseudo-pixels, as defined above,since each real pixel generated from each detector covers a relativelylarge area of the tooth image. In effect, such a camera generates“pseudo-pixels” in each digital frame image. Since fewer detectorelements are used in this embodiment, it will be appreciated that thecamera's overall cost can be reduced. Those skilled in the art willappreciate that a similar effect may be obtained in an alternativeembodiment by using magnification optics that only utilizes a smallportion of the camera's array in obtaining the image; however such anapproach wastes pixel information which has already been collected.

Those skilled in the art will appreciate that other closeness measurescan be used instead of the algorithms described above to achieve asimilar result. By way of example, other techniques of measuringsimilarity between two data sets can be used in determining a measure ofhow similar or close two data sets are. For example, one can arrange adata set as a vector so that the correlation coefficient is determinedas the cosine of the angle between data vectors. Cross-correlationfunctions or matched filtering can also be used beneficially. Theinterested reader is directed to any number of books on digital imageand signal processing, such as, for example, Netravali and Haskell,“Digital Pictures, Representation and Compression,” Plenum Press, 1988.Sections 1.1; 1.2; 1.3; 1.8; 1.9; 2.2; 3.2; and 3.3 of this book areincorporated herewith by reference for background purposes.

In still another embodiment, the shape of the grid of pseudo-pixelsdefining each tooth is selected in a manner dependent upon how the toothis positioned in the mouth. For example, an incisor tooth very nearlymaps to a shade guide; however, with reference to FIG. 14, a posteriortooth does not, particularly relative to the image capture position ofthe camera. Further, it will be appreciated that for purposes ofimproving the appearance of a smile, anterior teeth are considerablymore important than those in the posterior of the mouth. Thus, in apreferred embodiment it is desirable to provide more close matches, andcorrespondingly more dense and accurate grid patterns for the anteriorteeth. Accordingly, in a specific embodiment, grid shapes andcorrelation algorithms can depend upon tooth orientation within themouth and/or upon generalized tooth shape. In particular, anterior teethwill have a (proportionately) larger number of pseudo-pixels than teethin the back of the mouth for the same surface area.

An image of a tooth or tooth shade may be analyzed by a flood fillalgorithm to find the edges of the target tooth or tooth shade. Usingthis algorithm, from a point in the image (e.g., in the SNAPSHOT) knownto be in the tooth or tooth shade, adjacent pixels are considered onlyif that pixel is in a valid color range. The maximum extent is thenrecorded for the search in the X and Y directions, forming the outerlimits of the grid. In addition, contrast changes in groups of pixelscan be considered and used to determine the extent; but a black borderis easy to find.

In accordance with another important embodiment, “tooth shades”, as usedabove, are not used per se in defining a patient's tooth color. Rather,in a specific embodiment, a grid of pseudo-pixels is generated for thepatient's tooth; and these (pseudo-)pixels define the porcelain forrespective regions of the tooth. Pseudo-pixels are not actuallyrequired; and actual pixels can also be used in this manner to defineporcelain characteristics for each spatial location in the mouth.Reconstructive tooth material is then specified per pixel orpseudo-pixel. A data file generated from the SNAPSHOT or REAL IMAGE isthen processed to specify reconstructive materials with spatialprecision, as defined by pixels or pseudo-pixels. An acceptablequantification of RGB values, for example, can be used to tolerance boththe measurement and materials specification. For example, by associatingerror bars with each measure—e.g., R+/−ΔR, G+/−ΔG, B+/−ΔB, where the Δquantities are defined within certain practical tolerancelimits—reasonable tolerances can be achieved. Tooth shades operatesimilarly in that each shade results in a quantized color differencefrom every other shade; and thus the aforementioned tolerancingtechnique provides similar accuracy to the above-described correlationalgorithm. Unlike the tooth shade approach, however, spatial accuracyfor any given reconstructive tooth is generally determined only by thenumber of pixels or pseudo-pixels used in the reconstructive toothmanufacture; whereas a tooth shade has predefined color gradientsdefining the tooth shade regardless of the numbers of pixels orpseudo-pixels used. It will be appreciated that this approach avoids theuse of tooth shades at all, along with the possible confusion created bythe existence of alternate tooth shade guides.

The Color Measuring System and its Components

Cameras of the type required for use with this invention are generallyknown in the art and include, for example: INSIGHT™, manufactured in SanCarlos, Calif.; CYGNASCOPE™ offered by Cygnus Instruments, Inc., Goleta,Calif.; VISTACAM™ and others. In a preferred embodiment, the system ofthis invention uses a Welch-Allyn brand camera. Generally, it is desiredto use camera systems offering full-color imagery, which are capable ofcapturing a range of sizes, i.e., from the size of a typical patient'stooth preferably to images of the patient's whole smile.

In the preferred embodiment, it is advantageous for the camera to supplya minimum 640×480 pixel image to the PC software at 24 bits per pixel(i.e., 8 bits for each of the red, green and blue (RGB) components), orpreferably 30 bits per pixel. In a specific example, the system of thisinvention uses ALARIS QUICK VIDEO TRANSPORT frame grabber, providingdigitized images with at least 24 bits resolution. More specifically,the software can use a Twain protocol interface, as known in the art,which allows other cameras and frame grabbers to be tested without theneed for a change of software. Preferably, images captured by the cameraare displayed on a monitor screen to provide instantaneous feedback tothe system operator.

In another preferred embodiment, the resolution of the camera isspecified in terms of the Minimum Resolvable Color Difference that thecomplete system is able to achieve. This can be specified, for example,as the two RGB values of the two closest shades the system is requiredto differentiate. For example, the Chromoscop Shades 430 and 440 can beused to this end. In general, it is envisioned that the system should beable to differentiate between about 80 or more different shades. Anotherrequirement is that the system should be able to produce repeatableimages. That is to say that images of the same tooth taken at the samesession should not have a Δi of not more than 0.1, which is the amountneeded for the eye to perceive a difference. In a specific embodiment,the camera used in the system of this invention is a CMOS imager.

In terms of its physical setup, a stand-alone camera containing its ownlight source can be used, as explained below. A number of alternateembodiments are available in this regard. For example, in one embodimentthe camera can be battery powered. In this embodiment, the camera sitson a holder containing an inductive battery charger when it is not inuse. In another embodiment, when mounted on the charger the camera canbe coupled via an isolation sleeve (to be explained below) to acalibration target, for example, made of porcelain.

In a specific embodiment the output of the camera is supplied to adigitizer (such as a Sony digitizer) enabling convenient digital storageof the image. As noted above, the output of the camera can also besupplied to a frame grabber in a PC. Both options can be used in aspecific embodiment. In another embodiment, the output of the camera canbe supplied directly to a monitor (preferably positioned close to asurgery chair) and provide a digital output to a PC, which then need notbe close to the patient. As known in the art, the output could beUSB-type, or IEEE 1394.

In accordance with a preferred embodiment the digital output of thecamera also provides the opportunity to control the camera from a PC.Finally, in a preferred embodiment it is desirable to control the cameraso as to use it in two modes, i.e., normal image—for the mouth and fullface shots; and analysis image—in which color balance and automaticfunctions are disabled for tooth and calibration image, as describedbelow.

Turning now to the drawings, FIG. 1 shows a system 10 constructedaccording to a preferred embodiment of the invention. A solid state (orintra-oral) camera 12 connects to a computer 14 via a PC card 16 tocapture images through a wand 18. The solid state camera 12 includes adetector array 12 a including an array of detector elements 12 b, whichgenerate pixels in the digital images (e.g., SNAPSHOTS) captured by thecamera 12.

Through one of several known mechanisms, internal optics within the wand18 and/or camera 12 permit the capture of an image of a target object 20(for purposes of illustration, target object 20 is shown grosslyover-sized as compared to other elements in FIG. 1) by the array 12 a.By way of example, relay optics 18 a within the wand relays an image tothe array 12 a. A protection sleeve 22, discussed in further detailbelow (also grossly oversized for purposes of illustration), preferablyextends from the wand 18. As shown, the optics provide an opticalconjugate between the array 12 a and the target object 20 throughwell-known imaging techniques. Light captured from the target object 20enters the wand 18 for transfer to the camera 12 through an entranceaperture window 26.

The wand 18 generates light 19 to illuminate the target object 20through light ports 28. Preferably, light from the outside 30 of asleeve 22 is not permitted to illuminate the object 20 so that controlis maintained; and thus the sleeve 22 shields the target area 20 fromillumination by outside sources 30 (e.g., ambient room lighting).

An aperture 32 within the center of the end piece 34 of the sleeve 22 iswhere the tooth or tooth shade are placed so that a SNAPSHOT (i.e., adigital image of the tooth or tooth shade) can be made. As discussedabove, these SNAPSHOTS are processed to form REAL IMAGES (from realteeth) or REFERENCE IMAGES (from tooth shades or porcelains, etc.).

A black border 36 around the aperture 23 provides a good referencearound which the tooth or tooth shade are discernible within the digitalimage of the target area 20. The remaining area 38 about the border 36and within the end piece 34 is preferably a white reference sample,equally reflecting all light 19 from the light ports 28.

Finally, again with reference to FIG. 1, digital images from the camera12 are sent to the computer 14; and processing software 50 within thecomputer 14 processes these images to generate a CMN for each REAL IMAGErelative to the REFERENCE IMAGES. As discussed above, the software 50processes the CMNs to locate the lowest value CMN, indicating a match;and communicates the associated shade of that lowest CMN to the user viasignal line 52. As mentioned, other processing algorithms can bedeveloped to determine a best-fit match without departing from the scopeof the invention.

A representative digital image 31 captured by the camera 12 isillustrated in FIG. 2, showing an image 36′ of the border 36, an image38′ of the reference sample 38, and a tooth image 40. The entire image31 covers the target area 20 of FIG. 1. FIG. 2 also illustrates obviousregions 41 of the image 31 that would generate bad pixels since suchregions do not contain tooth imagery but rather other background imagery(e.g., the patient's gum).

FIG. 3 shows a blow up image of the pixels 42 (only representativepixels 42 are shown), which make up the tooth image 40 of FIG. 2. Inaccord with the invention, these pixels are transformed intopseudo-pixels 44 of FIG. 4. Each pseudo-pixel 44 is made up of all orsome of the real pixels within the area of the associated pseudo-pixel44. Two pseudo-pixels 44 b illustrate, for example, how a pseudo-pixelcan be generated from nine real pixels 42. FIG. 4 also illustrates thatan image can be made from either a real tooth 40 (resulting in a REALIMAGE) or a reference shade 40 (resulting in a REFERENCE IMAGE). REALIMAGES and REFERENCE IMAGES are correlated to find the composite matchnumber (CMN) as described above.

FIG. 5 shows another embodiment of an end piece 98 used in accordancewith a specific embodiment, that mounts to, or is made integrally with,the end of the sleeve (e.g., the sleeve 22, FIG. 1) and which has aseries of tooth shades 100 disposed in the end piece 98, so that foreach target 102 (e.g., the tooth or tooth shade), all relevantmanufacturing shades are provided in the same digital image, therebypreventing color contamination or other anomalies caused by time delay.As discussed above, when using the end piece 98 of this embodiment eachshade 100 is processed as a REFERENCE IMAGE and the tooth 102 isprocessed as a REAL IMAGE relative to those REFERENCE IMAGES to find aCMN. Preferably, a black border 104 surrounds the tooth aperture 106 andtooth 102. Also preferably, the remaining area 116 about the border 104and in the end piece 98 is a reference area. By way of example, thereference area 116 is a white reflecting region which can be sampled bydetectors that image that region 116. Further examples of the use ofreference area are discussed below.

Isolation Sleeve

In a preferred embodiment, an isolation sleeve is used to reducevariations in the images captured and processed by the system, and inparticular to eliminate light contamination from external sources. Inaddition, the isolation sleeve preferably keeps the reference shade andthe actual tooth at a set distance from the illumination source and thecamera optics. The sleeve also preferably sets the angle of illuminationbetween the source and the tooth so as to reduce reflections. Moreparticularly, the REFERENCE IMAGES and the REAL IMAGE are preferablytaken at the same illumination intensities, at approximately the samedistance, and without substantial specular reflections from the source.To this end, in a preferred embodiment the sleeve shields the cameradetector from imaging outside light and instead utilizes internallygenerated light (i.e., internal to the camera, for example, orassociated with an intra-oral wand attached to the camera) that can becontrolled. The sides (or side) of the sleeve are coated in a specificembodiment with a black material (e.g., a paint or a black mat paper, orblack felt), which reduces reflections along the sleeve to the tooth orreference shade. As used herein, “target area” refers to the imagegathering location that the system of the invention (i.e., that regioncaptured by the camera s detectors), including the REAL or REFERENCEIMAGE, as defined above.

FIG. 6 shows one end of wand 130 and a sleeve 132 constructed accordingto a specific embodiment of the invention. As in the example shown inFIG. 1 above, the wand 103 connects to a solid state camera (not shown,for purposes of illustration) to collect digital images of the targetregion 134 at the end of the sleeve 132. By way of example, the targetregion 134 includes an aperture (not shown) for imaging a tooth therein.Light 135 from the camera or wand 130 exits the wand 130 at opticalaperture 136 to illuminate the target region 134.

In a specific embodiment illustrated in FIG. 6, the sleeve 132 used inthe camera system of the present invention includes an accordion-likeexterior, which permits soft placement of the end of the sleeve onto thepatient's tooth. Preferably, such a sleeve is not entirely rigid so thatthe sleeve 132 can make contact without concerns about damaging thetooth. The outer portion of the sleeve 132 in this embodiment thus actssimilar to a spring, and an inner structural member within the sleevesets the final source-to-tooth distance once the outer sleeve/springcompresses to the desired location.

As shown in FIG. 6, the accordion-like sleeve 132 compresses between thetarget region 134 and the wand 130, as shown by compression arrow 138.In operation, a user of the wand/sleeve 130/132 pushes the sleeve 132 tothe patient's tooth, and the sleeve 132 compresses to providecomfortable (i.e., non-rigid) contact with the tooth. In a preferredembodiment, the sleeve 132 is spring-like to provide some force opposingcompression. This force increases until there is an interaction betweenthe sleeve 132, and/or the end piece of the sleeve 132 (i.e., the partof the sleeve at the target region 134), and the rigid structural member140 within the sleeve 132. The member 140 stops compression at a fixedlocation so that a set distance is achieved from the aperture 136 andthe target region 140; and so that a repeatable image size is attained.

Illumination

As noted, in a preferred embodiment, the camera system of this inventionincludes a light source that illuminates the target area. In a specificembodiment the sleeve 132 can be made to rotate so that images aregathered from difficult locations in the mouth. Preferably, the lightsource is tied to fiber optics which rotate with the sleeve so thatregardless of sleeve position the source-to-target area remainsapproximately fixed. In another aspect, the camera includes optics, suchas image collection optics and/or an entrance window. In an embodimentincluding this feature, the camera optics is tied to fiber optics, sothat images are captured effectively regardless of the position of thesleeve.

In another aspect, the sleeve used with the dental camera system of thepresent invention incorporates imaging optics which relay the toothimage through a Lyot stop, to prevent passage of unwanted light energyto the camera detectors. In a specific embodiment, the sleeveincorporates baffling—such as “two-bounce” optical stray lightbaffling—to reduce or substantially eliminate stray light from externalsources to the desired tooth image area.

FIG. 7 shows illumination arrangement wherein the source 150 of theilluminating wand 152 (connected to the solid state camera, not shown)is angled from the target area 154. As shown, the sleeve 156 connectedto the wand 152 is arranged adjacent to a patient's tooth 158, so thatdigital images can be taken of the tooth 158 (according to the practicesdiscussed herein) through the wand's optical entrance aperture 160.

For purposes of illustration, FIG. 7 also shows how light 162 emittingfrom the source 150 travels in a generally specular direction 164,reflecting off the tooth 158 into a direction 166 that is away from theaperture 160. Those skilled in the art will appreciate that scatteringdoes occur off the tooth 158 and into the aperture 160, but that thearrangement eliminates some unwanted reflections into the aperture.Light captured through the aperture 160 is relayed by optics (e.g.,fibers and/or relay lenses) to the camera's focal plane (not shown) togenerate digital images of the tooth 158.

FIG. 8 shows another embodiment of a sleeve 168 constructed according tothe invention to reduce passage of light 171 into the wand's entranceaperture 169 from sources 170 away from the target object (e.g., thetooth 172). The sleeve 168 is especially useful in imaging the tooth 172without adjacent proximity to the sleeve 168, as illustrated in FIG. 8.The sleeve 168 includes baffles 168 a known in the art, which require atleast one “bounce” and preferably two bounces of the light 171 prior togaining access to the entrance aperture 169, thereby significantlyattenuating “out of field” sources 170 (i.e., those unwanted sourceswhich might influence the color measure, e.g., room lighting). Forsimplicity, in this illustration the wand and solid state camera are notshown. Baffles 168 a can be placed within other sleeves shown herein toimprove out-of-field stray light rejection.

As noted above, in order to ensure high-quality images which do notdepend on the specific lightning conditions at the time the pictures aretaken, in accordance with this invention it is important to minimize theinfluence of such factors. Accordingly, in another specific embodiment,the sleeve used in the dental camera system of this invention includes areference sample disposed at the end of the sleeve, near the targetarea, so that: (a) color comparison information can be obtained; and/or(b) the camera has sufficient reflective surfaces from which toeffectively trigger the camera's auto-brightness and/or auto-colorfeatures. Specifically, as to feature (b), certain cameras available onthe market include electronics and software which automatically adjustbrightness and/or color in a digital image. Preferably, in thisembodiment such features are disabled. In the event they are operating,however, the reference sample is sized so that a sufficient reflectionarea is generated at the end of the sleeve, whereby the camera canoperate to capture good color images. By way of example, as to feature(b) above, the sample should be sized so that RGB values vary in acontrolled or calibrated manner throughout the reasonable tooth shadereflections (e.g., throughout all VITA Shades).

As to feature (a) above, one preferred embodiment utilizes the referencesample to obtain a color reference used to reduce variations in thedigital image. “Color” is based on “reflection”—that is, what the camerasees at the target area is based on reflection of whatever sourceilluminates the target. With the sleeve used in a preferred embodiment,the source is limited to the camera's illuminating source, therebyeliminating other sources and color variations that are not controllable(e.g., the ambient lighting in a building). It is well known that ablack body absorbs visible light; and a white object reflects the light.In one embodiment, therefore, the reference sample is as white aspossible so that it exhibits very little color (and particularly, thesample reflects light equally in the visible light range from betweenabout 400 nm to 800 nm). When using a white reference sample inaccordance with his embodiment of the invention, the following processoccurs:

1) Compute average RGB values (and/or other image variables such as hue)for several or all pixels imaged of the reference sample. This computedaverage is referred to as REF RGB.

2) For each digital image (i.e., for both REFERENCE IMAGES and REALIMAGES), subtract REF RGB from RGB pixel values for that image. Keeptrack of the sign (i.e., positive or negative) of the result. The resultis referred to as “REF RELATIVE RGB” (i.e., image RGB—REF RGB).

3) Utilize a correlation algorithm, such as described above, (i.e., forthe CMN) on REF RELATIVE RGBs as opposed to absolute RGB values (for thepseudo-pixels). Note that when the RSS (i.e., subtract and square) ofthe CMN algorithm is computed, the sign of the REF RELATIVE RGB matters.For example, if the REFERENCE IMAGE RGB is −0.1,−0.5,−0.6, and the REALIMAGE RGB is 0.1, 0.7, 0.9, then this REAL IMAGE has quite a bit morecolor difference (compared to the REF IMAGE, which is the importantquantity) than, e.g., a REAL IMAGE with −0.5, 0.2, 0.1. Afterwards, thesquare of the RSS destroys the sign importance.

The reference sample compensation algorithm described above is used in aspecific embodiment to compensate for certain variations. Thus, theauto-brightness feature of certain cameras changes the color of thelight emitted from the camera (this is sometimes referred to in the artas the color temperature). Unfortunately, the emitted RGB is not knownexcept for the reference sample, which reflects the source light back tothe camera detectors. A good reference sample will thus reflect nearlyall colors equally. Since one is interested in differences between REALIMAGES and REFERENCE IMAGES, the real concern involves differences andnot absolute colors.

The reference sample compensation thus also compensates for imageacquisition changes which occur over time. For example, the source mayemit more or less light, over time, even over several minutes or hours;and it would be desirable to eliminate such variations to increase thesensitivity to color comparisons. The passage of time during an imageacquisition sequence only adds to the variability in the measurement:the source color temperature may change, the detector sensitivity orgain may change, etc. With the above reference sample adjustment, if forexample one has a perfect white tooth, then its REF RELATIVE RGB is0,0,0. Assuming that a tooth shade exists that was also perfectly white,it would have a REF RELATIVE RGB of 0,0,0—creating a match.

In another embodiment, the white reference is integrated to find REFRGB, per frame. REF RGB is then subtracted from each pixel RGB in theimage (or the other way, i.e., image RGB subtracted from REF RGB, aslong as consistent throughout every measurement). In another embodiment,REF RGB is subtracted from pseudo-pixels; but preferably REF RGB issubtracted from real pixel RGBs.

In another embodiment, the sleeve used with the dental camera system ofthe present invention is formed in the following way. At the end of thesleeve, a central aperture exists preferably in the middle of the targetarea (e.g., an object such as a tooth or shade is placed at theaperture). Surrounding the central aperture is a black border, toprovide high contrast at the edges of the target object. A target objectsuch as a tooth is thus readily defined and discerned within the blackborder. The aperture also fixes the size of the image for the tooth ortooth shade. Some or all of the remaining area at the end of the sleeve(captured by the camera detectors) in the target area is a whitereference sample.

The amount of white reference sample in the target area can be chosenexperimentally. By way of example, the average mid point in theauto-brightness (if operating) is obtained so that on average REF RGBchanges little. The size of the white sample in the target area isadjusted in area until REF RGB is minimized for all shade values, e.g.,A1-A4, B1-B4 and soon. With more black in the image due to lessreference sample area, the auto brightness control on the camera (ifapplicable) adjusts to higher gain to ‘balance’ the intensity of theimage, causing the reference and sample parts to saturate in the red andgreen.

As noted above, in a specific embodiment, the walls of the sleeve areselected mat black to eliminate reflections, but the facing platecontaining the target area is bright to force the camera gain downwards,out of non-linear color operability. In this embodiment preferably thecamera's auto features are turned off (and at least any white balance isset to manual). In one specific embodiment, the reference sample is madeof a light colored felt material. In alternative embodiments, the sleevewalls are made of a felt material. In these embodiments, the feltmaterial has elements which extend away from the material producing moreof a lambertian surface. Such surfaces are preferred as they reduceunwanted specular reflections. Also, the sample reference produces anexcellent image when it is not specular. Alternatively, a black velourpaper can be used in the sleeve, such as by JL Hammett Co.

FIG. 10 illustrates a non-contact re-imaging system 250 used inaccordance with another embodiment of the present invention to image atarget tooth 252 without contact between the tooth 252 and a sleeve 254.Optics 255 reimage the tooth 252 internal to the sleeve 254, at internalimage 256, and a Lyot stop 258 is used to reduce unwanted stray lightentering the aperture 260 to the camera (not shown).

FIG. 11 illustrates a non-contact re-imaging system 300 used to image atarget tooth 302 to a digital camera 304, and without contact betweenthe tooth 302 and the system 300 or camera 304. Although this reimagingsystem 300 can be made in several forms, in one embodiment the system300 includes a sleeve 306 that permits hand-held manipulation into apatient's mouth to capture the digital image of the tooth 302. By way ofexample, optics 308 reimage the tooth 302 internal to the sleeve 306, atinternal image 310, and a stop 312 is used for color referencing inanalyzing the tooth color. Stop 312 forms an aperture defined by edge312 a. FIG. 12 illustrates one digital image 320, as taken by camera304, of the tooth 302 and the inside view of stop 312. The region 322defines that region inside the patient's mouth that is not the patient'stooth 310. Region 324 consists of a color reference which is used asdescribed herein to relate and compare to color pixels of the digitalimage of the tooth image 310, so as to better define tooth color. Region324 is preferably the inside of stop 312.

Those skilled in the art will appreciate that a reimaging system such asin FIG. 11 can be made in several ways. By way of example, system 350 ofFIG. 13 shows one system of the invention to reimage a tooth 352 to aninternal image 354 for reimaging into a digital camera 356. As above,camera 356 takes SNAPSHOTs of the tooth 352, for color analysis. Opticalelement 358 images the tooth into optical fiber bundle 360, which relaysthe image from one side 360 a to the other side 360 b of the bundle 360,as known in the art. Optical elements 362 provide for reimaging to formthe internal image 354 at the stop 364. As above, the stop 364 has areference color disposed thereon, facing camera 356, so that a referencecolor image is attained such as in FIG. 12. Fiber optic bundle 366relays the image 354 from side 366 a to 366 b, and exit optics 368provides for relaying the tooth image to the camera 356. One convenientfeature of system 350 is that fibers 366, 360 can be flexible; and asleeve 370 can support these elements to provide a hand-held wand thatcan be inserted into a patient's mouth to acquire the image. Camera 356can provide its own light source 356 a which generates light 356 b backalong the optical path taken by tooth image 354. The advantage of thisis that source 356 a can be carefully selected for its colorcharacteristics to facilitate tooth color detection; and further light356 b can illuminate stop 364 inside the sleeve or wand 370 so that thecamera 356 can detect and compare its color to the tooth's color image354.

Tooth Restorative Processing

FIG. 14 shows certain tooth restorations and decays, which illustrationscan help understand more fully aspects of the invention discussed above.A healthy tooth, free from any decay with no current restoration(“restoration” is any part of a tooth that is replaced with a materialthat allows the tooth to remain in the mouth as a functioning and wholestructure) is referred to as a “virgin” tooth. Despite advances inpreventative treatment and services (fluoridated water, fluoridetreatments, sealants—which are unfilled resins that are bonded into deepgrooves of posterior or back teeth to prevent decay in those areas), 50%of American children by age 12 have occlusal decay (decay in the top, orbiting surface) in permanent molars which erupted or came into theirmouths at age 6.

Typical progression of decay in a tooth is as follows: Following C.V.Black's classifications, a tooth can require a restoration in thefollowing positions:

CLASS 1—occlusal area, that is, within only the top or biting surface ofthe tooth, usually beginning in the groove or crevice. This term is usedonly for posterior (back) teeth, i.e., molars and premolars.

CLASS 2—area made up of occlusal and one or more sides of the tooth,either mesial (wall towards front) and/or distal (wall towards back) andor buccal(wall towards cheek) and or lingual(wall towards tongue) sothat a class 2 restoration may be termed “MO” (mesial-occlusal), “MOD”,“OB”, etc.

CLASS 3—area of an anterior, or front, tooth involving only aninterproximal wall, that is mesial or distal, areas that faceneighboring teeth.

CLASS 4—area of an anterior tooth involving the incisal (bottom) edgeand an interpoximal wall.

CLASS 5—area of any tooth on only the buccal or lingual wall

CLASS 6—area of a tooth involving the cusp tip (cusp being the highestpoint of the tooth, like the mountain peak; this would apply to canines,premolars, and molars)

Once decay is detected, through clinical examination, radiographs, etc.,the decayed portion of the tooth needs to be removed. This is achievedthrough the use of a handpiece (drill). Once excavation of decay iscomplete, the remaining tooth structure is evaluated for restorationpossibilities. A “filling” is placed if 50% or more of the toothremains, with the stress-bearing areas of the tooth remaining intact(such as cusps and walls of the tooth which are active in biting andchewing process). If these areas of the tooth are compromised, alaboratory-processed restoration is required.

Consider a specific example, in which it is assumed that the tooth needsa restoration, which will be placed right in the office, say a MO on amolar. The choice of materials is made, which could be either amalgam(silver, not done much any more), or composite or ceromer, which aretooth-colored direct materials (Matrix of ground plastic and/or glass ina bis- GMA resin). A shade needs to be selected for the material, suchas described herein in accord with the invention. The tooth is cleanedand isolated from saliva and blood by use of cotton rolls, matrix bands,possibly a rubber dam. The tooth surface is etched with a cleanser(typically 37% hydrophosphuric acid), rinsed, and treated with anadhesive, which is bonded to the tooth by use of a curing light—a lightwith a wand attachment that is about 11-13 cm in width and emits a lightin the range of 400-500 nanometers. The material is then placed into thecavity by hand instruments or via dispensing through a carpule/cartridgesystem in a syringe. The material is somewhat condensed into place at2-3 mm intervals, and light cured in between. Upon final filling, therestoration is polished and contoured using finishing burs (tips) on thehandpiece (drill).

If the tooth requires a lab fabricated restoration, such as an inlay,onlay or crown, further steps need to be taken (Inlay being a Class 2restoration NOT including cusps, onlay being a Class 2 restorationincluding cusps, crown being full, or total coverage of the tooth). Thetooth is shaped to make the final shape not have any undercuts, withwalls as parallel as possible for retention purposes.

Then an impression, or mold is taken of the tooth, which is in amaterial that remains accurate despite temperature changes, moisture,pouring stone into the mold and removing it several times. An impressionof the opposite arch of teeth, or opposing arch, is taken also so thatthe technician can articulate, or put together the two arches andsimulate the patient's mouth or bite. A registration of such a bite canbe taken also and sent with the case. So that the things sent to the labfor such a case are: impression of the tooth to be restored and adjacentteeth, model or impression of opposing teeth, and possibly a biteregistration.

Those skilled in the art should appreciate that the invention todetermine the appropriate color shades of the tooth as illustrated inFIG. 14 can be accomplished by the methods herein, and/or by systemsdisclosed in the several figures. Using a wand of the invention,furthermore, various teeth (as in FIG. 14) can be acquired for digitalevaluation. In accord with the invention, digital files of patients'teeth can be stored in memory of computer 14, FIG. 1, for a permanentrecord. A patient can then be evaluated over time for color changes.

MISCELLANEOUS ASPECTS

Although the VITA™ Shade guide is often discussed herein, it should beapparent that other shade guides and porcelains can be stored asREFERENCE IMAGES and compared to REAL IMAGES in alternative embodimentsof this invention. Computer memory can store a large number of images,even from different manufacturers, so as to provide the optimum colorfit to a patient's tooth. By way of example, IVOCLAR has one suitableshade guide, as well as various materials of porcelains, ceromers,polymers, and others. In accord with the invention, a database can storeREFERENCE IMAGES for match correlation to REAL IMAGES. Alternatively, inone aspect, the invention performs a conversion to other manufacturershades and or porcelains so that alternative laboratories can be usedwithout undue concern for manufacturer alliance. Specifically, in accordwith one aspect of the invention, a conversion between known shadeguides is provided for increased lab selectivity. It will be appreciatedthat the conversion of digital images involves mapping from one set ofcolor coordinates to another, which procedure is well known in the artand need not be considered in further detail.

As described, one major problem due to auto brightness is that if thereis not enough light material in the image, the auto brightness turns thegain up too high, and the R and G values saturate in the sample. Byadding sufficient light colored reference area, the balance of light todark is better, but the reference can saturate in places. This can becompensated some by using an end plate at the end of the sleeve thatwill be all white but with the black border round the sample aperture. Areference color area can be included in one corner so that the cameraadjusts brightness for the constant white area leaving the reference andsample somewhere in the middle of the operable RGB ranges.

In still another aspect, instead of subtracting the RGB from thereference sample, an average of the reference sample is used.Specifically, over the range of images taken, an average REF RGB(denoted “AVE REF RGB”) is determined for the reference sample. For eachindividual image, the difference is calculated between the REF RGB andthe AVE REF RGB. This delta RGB is then added to the image RGB tocorrect for any compensation in the camera. Thus if the image isbrighter than the average image, the difference is subtracted from thesample values and vice versa.

In still another aspect, the reference sleeve has an end plate whichcontains all tooth shades for a given manufacturer (so that one sleeveis used for a particular manufacturer). Any image therefore acquires thesample tooth as well as all the tooth shades; and image processingcommences on the one digital image. This is advantageous in that cameracolor drift is compensated for since all images are taken at the sametime.

When determining tooth color, if the shade does not correspond to anexisting shade (such as Al, D4), a system 400 is provided as shown inFIG. 15 which will create a recipe for whatever shade the tooth is.Color digital information about the tooth under test is sent to system400 over a communication line such as the Internet; and system 400selects porcelain mixtures from supply 402 to be sent and mixed withinmixing subsystem 404. Subsystem 404 dispenses the mixture into a capsule406 for the dentist, which administers the final mixture to thepatient's tooth.

The new shade material in carpule 406 is either provided chair-side, orreported to the technician over the Internet 410 (in which case, system400 can be present at the technician's site). If for example the dentistneeds to use a composite material like HELIOMOLAR by Ivoclar, and thedesired shade is something between C2 and C3, the system determines thenew shade of “C2/C3”, mixes component composite materials accordingly,and dispenses to the dentist a premixed carpule/cartridge 406 ofmaterial to be used on that patient. Information to be sent to the labcan include a recipe that will instruct the technician as to how tocreate the new shade using whatever material is selected—porcelain,ceromer, pressed porcelain, etc.

FIG. 16 illustrates in a block-diagram form the configuration of theinteractive network system in a preferred embodiment. As shown, thissystem is implemented as a (preferably website) server 1610, havingaccess to one or more databases 1630 containing information aboutdifferent aspects of dental restoration. As noted, this information in apreferred embodiment includes materials, procedures and preparationrecipes related to various dental restoration prostheses, and mayinclude preparation design, recommended burs to achieve such apreparation, recommended temporization materials, cements that should beused with that given material, instructions on how to use such a cementand where to buy such materials, and others. In addition, database 1630may contain information about different dental procedures, and inparticular answers to commonly asked questions. In yet anotherembodiment, the database may also contain patient histories, so that adentist (or a technician) having access to the system can read thepatient history regardless of where they arc located physically,provided that they have proper authorization to access this information.The database may further be connected to external information source(s)providing input from product manufacturers, market research or others.In accordance with the present invention there is no restriction on thetype of database 50 design that can be used.

In operation, users can access the service over a communications network1620, such as the Internet, using data entry devices, designated 1640 inFIG. 16. Generally, devices 1640 can be implemented as any color-displaydevice capable of communicating over the network 1620. In the preferredembodiment where the network is the Internet, for example, suchcapability is provided by browsers, as known in the art. Thus, a device1640 can be a conventional personal computer 14, as illustrated in FIG.1. In alternative embodiments that do not communicate over the Internetsuch a device should have a capability to communicate over acommunications network, e.g., an intranet, as known in the art.

In a preferred embodiment, the server 1610 is a computer, the type ofwhich may range from a personal computer to a workstation or a largercomputer or a network of computers. The choice of a specific computersystem is based on known trade-offs, and thus will not be discussed infurther detail. In the preferred embodiment, the server isInternet-enabled but it will be appreciated that in alternativeembodiments it can support another network, e.g., an intranet. Broadly,the server 1610 comprises a processor 1650 and random access memory(RAM) and read-only memory (ROM), collectively designated 1670. Theprocessor 1650 is adapted to execute instructions in different computerlanguages and can operate in different operating system environments,such as the PC/Windows™ environment. In a preferred embodiment, theserver also has a data formatting device 1660 serving to provideinterface with the database(s) 1630. In various embodiments the servercan be provided with additional devices (not shown) such as apoint-and-click device (like a mouse), keyboard, a monitor and variousother devices, which may include, for example a printer 46. Preferably,the server is equipped with means for connecting to externalcommunications media, and may include various connectivity types, suchas a LAN connection.

It will be appreciated that using the system shown in FIG. 16, differentusers 1640 can access information stored at the network server (or towhich the server has access). It will also be appreciated that thesystem would enable direct communication between users, such as on-linecommunication between a dentist and a dental restoration laboratory,where the two sides can simultaneously have access to a patient record,an image of tooth in need for restoration or others. Naturally, ifdesired, such communications can be established over dedicated linesalthough in accordance with this invention it is desirable to use opensystems, such as the Internet because of the flexibility they provide.Further, while they are shown separate for illustration purposes, itshould be apparent that the server 1610 can physically be located atdentist's (or laboratory) office. Communications networks and servers ofthe type illustrated in FIG. 16 are generally known in the art and thusneed not be described with specificity.

The content of U.S. Provisional Applications Nos. 60/106,920 filed Nov.3, 1998, 60/109,299 field Nov. 19, 1998, 60/120,596 filed Feb. 18, 1999and 60/120,620 filed Feb. 18, 1999 are expressly incorporated herein byreference thereto.

While the invention has been described with reference to the preferredembodiments, it will be appreciated by those of ordinary skill in theart that various modifications can be made to the structure, form andoperation of the various embodiments of the invention without departingfrom its spirit and scope, which is defined in the following claims.

APPENDIX A contains, for disclosure purposes, non-limiting source codefor use with certain aspects of this invention.

What is claimed is:
 1. An interactive dental restoration method betweena dentist and a dental restoration laboratory which comprises:identifying a dental restoration need in a patient; designing apreliminary treatment plan that includes prosthesis materials and designcriteria for preparation of a dental prosthesis to be placed in thepatient to satisfy the dental restoration need; transmitting thepreliminary treatment plan via a communications network to a dentalrestoration laboratory; and communicating a final treatment plan,including modifications to the preliminary treatment plan if necessary,to the dentist.
 2. The method of claim 1 wherein the dentist preparesthe preliminary treatment plan and the design criteria include digitalimage representations of the dental restoration need.
 3. The method ofclaim 2 which further comprises evaluating the preliminary treatmentplan at the laboratory before communicating the final treatment plan tothe dentist.
 4. The method of claim 3 which further comprisesimplementing the final treatment plan in the patient and transmittinginterim preparation information to the laboratory for survey withconfirmation prior to completing the final treatment plan.
 5. The methodof claim 4 wherein the design criteria include tooth preparation andproposed decay excavation, and which further comprises communication, aconfirmation or modification, from the laboratory, of the acceptabilityof one or more of the proposed design criteria.
 6. The method of claim 3when the step of transmitting and evaluating the plan are codirectedover the communications network.
 7. The method of claim 6 which furthercomprises preparing a dental prosthesis that satisfies the designcriteria of the final treatment plan and placing the prosthesis in apatient.
 8. The method of claim 7 which further comprises verifying thatthe dental prosthesis is prepared according to the final treatment planprior to placement of the dental prosthesis in the patient.
 9. Themethod of claim 7 wherein at least one of the design criteria or themodifications include proposed decay excavation, tooth preparation,prosthesis materials or prosthesis color.
 10. The method of claim 7wherein the digital image representations include REAL IMAGE andREFERENCE IMAGES and the modifications include correlation of a colorselection for the prosthesis to match the REAL IMAGE.
 11. Acomputer-based dental restoration system comprising: a network serverhaving a database storing information about materials, procedures andpreparations concerning dental restoration prostheses; a communicationsnetwork providing access to said network server at least between adentist and a dental restoration manufacturer; and one or more computersfor accessing information stored at the database over the communicationsnetwork and displaying the information in a humanly readable format. 12.The dental restoration system of claim 11 wherein the computer(s) can belocated at a dental office and the communications network is theInternet.
 13. The dental restoration system of claim 11 whereininformation stored in the database comprises prosthesis materials,preparation diagrams, reduction dimensions, margin design and burs forspecific dental restoration prostheses.
 14. The dental restorationsystem of claim 11 wherein the database further stores informationconcerning one or more patients having dental restoration needs.
 15. Thedental restoration system of claim 11 wherein the network server furthercomprises application programs for enabling users to query the databaseregarding specific materials and procedures concerning dentalrestoration prostheses for confirmation, verification, modification orevaluation of the same.
 16. The dental restoration system of claim 15wherein the one or more computers at the dental office receive answersfrom the database to said queries and further comprising at least oneprinter located at the dental office to print said answers for referencein carrying out the treatment plan.
 17. The dental restoration system ofclaim 11 further comprising at least one computer at a dentalrestoration laboratory, said at least one computer having access to thenetwork server and said or more computers at the dental office over thecommunications network.
 18. The dental restoration system of claim 11further comprising a digital camera for taking digital images ofpatient's teeth in need of dental restoration and a communication linkfor transmitting the digital images to the one or more computers at thedental office.
 19. The dental restoration system of claim 18 wherein theone or more computers at the dental office stores the digital images ofpatient's teeth in need of dental restoration and the communicationsnetwork forwards the digital images to the database for storage therein.20. The dental restoration system of claim 11 wherein at least twocomputers are utilized, one located at the dentist's office for use bythe dentist and one located at the dental restoration manufacturer'soffice for use by the dental restoration manufacturer.